1. Field of the Invention
The present invention relates to an electronic blurring compensation device for electronically compensating blurring of a shot image.
2. Description of the Related Art
A large number of image pickup devices for picking up still images and motion images while using a solid-state image pickup element are structured to be shot by grasping with hand. In such image pickup devices, for example, when the luminance of a subject is low, the shutter speed becomes slow, and it is known that blurring of images due to hand movement may easily occur. It is also known that due to vibration during a drive, a camera mounted to a car or the like, blurring of images may similarly occur.
Various technologies for compensating such blurring are proposed up to now and example of which include an optical blurring compensation for shifting an optical system in accordance with vibration, a sensor shift blurring compensation for shifting an solid-state image pickup element in accordance with vibration, and an electronic blurring compensation for compensating blurring by performing a processing on a picked up image.
Among these electronic blurring compensation techniques, one corresponds to motion images for keeping the position of a subject in the images by differing image cutup positions in accordance to blurring, but this technique cannot be applied to still images because the technique is not designed for avoiding blurring of an image in one frame.
On the other hand, various electronic blurring compensation techniques that can be applied to still images are also proposed.
For example, Japanese Unexamined Patent Application Publication No. 2001-45359 describes an image pickup device for subsequently reading out a plurality of images from an image pick up element, storing the images in an image memory, and thereafter compensating mutual blurring among these plural images to synthesize the images, thereby generating an image in which the blurring has been compensated.
In addition, Japanese Unexamined Patent Application Publication No. 2005-198148 describes a solid-state image pickup element including a charge transfer section for horizontally and vertically transferring an image into an image pickup element, in which relative blurring between a picked up first image and a second image that has been transferred to the charge transfer section is compensated and the first image and the second image are synthesized to each other, thereby generating an image in which the blurring has been compensated.
The technique described in each of the above-mentioned publications is aimed at obtaining one image by performing the synthesis after adjusting the relative positions of the plurality of images. Incidentally, when one synthesized image is generated by compensating mutual blurring among n images (n is a positive integer) which are shot in a time-division manner, an area whose number of images synthesized does not reach n is developed at an end portion of the generated synthesized image. Such area whose number of images synthesized does not reach n has gradually smaller luminance as compared with the area where n images are synthesized one another, so it is necessary to cut and remove the area or perform a compensation process on the area. This area whose number of images synthesized does not reach n is narrow enough to ignore as compared with the size of the whole image in a usual case, and the compensation requires a complicated process. Thus, adoption of the cut and removal method is simple and practical. However, for a device to be used by a large number of general users such as a camera, blurring becomes extremely large in accordance with a skill of a photographer, and it is also considerable that the effective image area may be unacceptably narrow.